Conventional temperature transducers include resistance-temperature detectors, thermistors, thermocouples, and integrated sensors. The thermocouple is a passive device which senses temperature using known thermoelectric principles. Thermocouples provide approximately linear changes in voltage corresponding to small changes in temperature.
Conventional thermocouples are generally fabricated by welding two dissimilar wires. Using conventional thermocouples to measure temperature gradients across a large area involves the fabrication of a thermocouple array connected to a voltmeter with a sequential scanner.